Conventionally, mirrors which reflect the rear side (including the rear lateral sides) of a vehicle are arranged on the lateral sides of the front portion of the vehicle, and the vehicle is configured such that the driver can confirm the situation on the rear side by viewing the mirrors.
On the other hand, in recent years, systems in which an image of the rear side of the vehicle is captured by attaching an imaging unit instead of the mirror and the captured image is displayed on a meter panel or the like have been studied. According to such systems, the driver can confirm the situation on the rear side of the vehicle without greatly averting the driver's eyes from the forward direction.
Patent Literature 1 discloses a rearward imaging device which is provided with an imaging unit and a housing for housing the imaging unit, and captures an image of the rear side of the vehicle.
In the rearward imaging device according to Patent Literature 1, a concavity having the shape of a bottomed cylinder is formed in a rear portion of the housing. A lens which is held in a barrel of the imaging unit, or a lens filter which covers the lens, is arranged at the bottom of the concavity, and the imaging unit captures an image of the rear side of the vehicle through the bottom of the concavity. Hereinafter, the lens or the lens filter which is held at a tip end portion of the barrel is referred to as “the transparent member”.